The use of screw piles is an alternative to the use of concrete foundations in different residential, commercial, recreational or agricultural applications. Resembling large screws, screw piles are typically installed deep into the ground to support structures such as decks, sun rooms, cart ports and the like.
A screw pile generally includes an elongated cylindrical, hollow pile body having the general configuration of a metal pipe. The hollow pile body comprises an upper end and a lower end to which is welded a helical member, which is used to screw the pile into the ground and to provide vertical stability once the screw pile is properly installed. Mounted to the upper end of the pile body is a pile head configured to receive or support a structure.
Various configurations of the pile heads are known. In some configurations, the pile head simply consists of a plate or platform fixedly attached to the upper end of the pile body (e.g. by welding), which extends generally horizontally when the screw pile is installed. In other configurations, a plate or platform is fixedly attached to an adaptor which can be received and rest on the upper end of the pile body. In such configurations, the adaptor generally takes the form of a relatively short cylinder having a diameter smaller than the diameter of the pile body. Once pile head is mounted to the pile body, the adaptor is received in a cylindrical cavity defined at the upper end of the pile body while the plate or platform abuts the upper edge of the pile body, thereby preventing downward movement of the pile head relative to the pile body. In such configurations, the screw piles do not offer an adjustment of the height of the platform once the screw pile is installed which may, in some instances, require further positioning of the entire screw pile relative to the ground. Since the installation of screw piles generally requires the use of relatively heavy equipment, such adjustment may be burdensome and provide unsatisfactory results.
In other configurations, the distance between the platform and the upper end of the pile body is adjustable. In known configurations, pile heads typically include an adaptor resting on the upper end of the pile body, the adaptor comprising a relatively short cylindrical member receivable into the cylindrical cavity of the pile body and a circular plate welded to the upper end of the short cylindrical member and designed to rest on the upper edge of the pile body (see FIG. 1). Defined on the circular plate of the adaptor is a bore for adjustably mounting a platform. In such prior art configuration, the platform includes a bolt having a lower end and an upper end to which is welded a plate. The bolt is sized such that its lower end is slidably engageable in the bore of the adaptor. To allow modification or adjustment of the distance between the plate and the adaptor, and thereby provide vertical adjustment to the pile head, a nut is provided. The nut sized and shaped to engage the threads of the bolt while resting on the circular face of the adaptor. Once a structure is mounted on the platform, adjusting the distance between the top of the pile body and the structure is made possible by turning the nut in one direction (to move the platform upwardly) or in the other direction (to move the platform downwardly).
As it will be appreciated, the bore defined in the circular plate of the adaptor must be sufficiently large to allow vertical displacement of the bolt therein, without damaging the threads. Therefore, when the screw piles offer adjustment, the bolt tend to be loose in the bore and some lateral movement of the bolt is susceptible to occur relative to the adaptor (see FIG. 1), which lateral movement is transferred to the plate and the structure mounted thereto. Further the screw piles of the art tend not to be satisfactory because they are not adapted to prevent upward movement of the structure relative to the screw pile (e.g. in instances of high winds lifting structures such as decks) because the adaptor is maintained into position of the pile body by gravity. To avoid such upward movement of the platform, it is still possible to fasten the platform to the top of the pile (e.g. by welding). This, however, is difficult to achieve on the field and, alternatively, makes the installation of the pile more complex if the platform is already attached to the pile at the time of installation.
Therefore, there exists a need for a new screw pile that alleviate at least some of the drawbacks of the prior art.